1. Field of the Invention
This invention relates to a poly(arylester-carbonate)s and process for the preparation of poly(arylester-carbonate)s.
The present invention particularly relates to the application of the mono-alkylcarbonate of bisphenols for the synthesis of a variety of poly(arylester-carbonate)s. Poly(arylestercarbonate)s are a class of engineering plastics which are commercially produced by the industry for replacing glass, metals, etc. They find wide application either as such or in blends with other well known polymers such as poly (ethylene terephthalate), poly(butylene terephthalate), etc. The introduction of a carbonate linkage in the matrix of a crystalline polyester has the beneficial effect of improving processability, reducing the glass transition temperature and improving impact strength.
2. Description of Related Art
Poly(arylester-carbonate)s are generally prepared by a melt polycondensation process involving bisphenol-A, aromatic dicarboxylic acid and diphenylcarbonate at 280.degree. C. and 5 mm Hg pressure in presence of a suitable catalyst, [Japan patent 01,247,420 (1989); Japan patent 8098,228 (1980); Eur. pat. Appln. 303, 93 (1989) .
Alternatively, an interfacial polymerization technique can also be used wherein the sodium salt of bisphenol-A is reacted with a mixture of acid chlorides of aromatic dicarboxylic acid and phosgene in two phase medium consisting of water and methylene chloride as solvents and in presence of a phase transfers catalysts (G. S. Kolesnikov et al, Vysokomol, soedin, set. B, 9:49 (1987), Ger. offen. 2,009,49 (1971).
There are many inherent limitations in the currently available processes. In the malt polymerization process three reactants are involved whose relative proportions have to be carefully maintained in order to produce high molecular weight polymers. Furthermore, the process uses diphenylcarbonate which is very expensive. The interfacial process uses corrosive and toxic phosgene and produces sodium chloride by-product. In addition, organic solvents are used.